题解 | #日期差值# - 练练工程

#include <iostream>
#include <string>
using namespace std;
class Date {
public:
    Date(string& s) {
        _year = stoi(s.substr(0, 4));
        _month = stoi(s.substr(4, 2));
        _day = stoi(s.substr(6));
    }
    bool operator<(const Date& d) const {
        if (_year < d._year) {
            return true;
        }
        else if (_year == d._year && _month < d._month) {
            return true;
        }
        else if (_year == d._year && _month == d._month && _day < d._day) {
            return true;
        }
        else {
            return false;
        }
    }
    bool operator!=(const Date& d) const {
        return (_year != d._year) || (_month != d._month) || (_day != d._day);
    }
    int GetMonthDay(int year, int month) const {
        static int monthDayArr[13] = { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
        int day = monthDayArr[month];
        if (month == 2 && ((year % 400 == 0) || (year % 4 == 0 && year % 100 != 0))) {
            day += 1;
        }
        return day;
    }
    Date& operator+=(int day) {
        _day += day;
        while (_day > GetMonthDay(_year, _month)) {
            _day -= GetMonthDay(_year, _month);
            _month++;
            if (_month == 13) {
                _year++;
                _month = 1;
            }
        }
        return *this;
    }
    Date& operator++() {
        *this += 1;
        return *this;
    }

    int operator-(const Date& d) const {
        Date max = *this, min = d;
        if (*this < d) {
            max = d, min = *this;
        }
        int cnt = 0;
        while (min != max) {
            ++min;
            ++cnt;
        }
        return cnt + 1;
    }

private:
    int _year;
    int _month;
    int _day;
};
int main()
{
    string a, b;
    cin >> a >> b;
    Date d1(a);
    Date d2(b);
    cout << (d1 - d2) << endl;

    return 0;
}